Apparatus and process for the preparation of detergent compositions



June 1970 M. D. REINISH ErAL 3,515,672

APPARATUS AND PROCESS FOR-THE PREPARATION OF' DETERGENT COMPOSITIONS Filed July 24, 1965 3,515,672 APPARATUS AND PROCESS FOR THE PREPARA- TION OF DETERGENT COMPOSITIONS Martin David Reinish, Emerson, and Lowell Ashton Ledgett, Ridgewood, N.J., assignors to Colgate-Palmolive Company, New York, N.Y., a corporation of Delaware Filed June 24, 1965, Ser. No. 466,795 Int. Cl. Clld 9/10 U.S. Cl. 252109 26 Claims ABSTRACT OF THE DISCLOSURE An apparatus and a process for preparing detergent compositions having a low bulk density in which a slurry is continuously mixed with an additive material one of these components being difficultly flowable because of its high solids content and in which the proportions of these components are carefully controlled and in which they are mixed under conditions of high shear, the high shear mixing being performed in the presence of a normally gaseous substance.

This invention relates to an apparatus and process for the preparation of detergent compositions having a low bulk density and more particularly to a process whereby said low bulk density detergent compositions can be obtained in a facile and economical manner.

In accordance with the present invention, a 10W bulk density detergent composition is economically prepared by forming the detergent material in such a manner as to minimize the water content of the composition immediately prior to the drying step thereby reducing the need for large quantities of drying heat, and large drying apparatus. This process, described in more detail hereinafter, enables significant reduction of the cost of preparing such compositions. In addition, the present invention produces a low bulk density detergent composition by the use of a process and apparatus allowing control over the product properties thereby enabling consistent production of a uniform product. The term low bulk density as used herein refers to compositions having an apparent density of less than about 0.45 gram per cubic centimeter. By apparent density is meant the weight per unit volume of the material indicated by the context. Thus, in the case of freely flowing particulate products, the term refers to the untamped weight per unit volume of the particulate material as it is charged into the container.

The present invention provides a process for the preparation of a solid detergent composition having a low bulk density which comprises forming a slurry including a continuous aqueous phase and a dispersed phase containing an organic detergent, and at least one inorganic alkali or alkaline earth metal salt selected from the group consisting of alkaline and neutral detergent builder salts. The slurry is intimately mixed at a high shear rate after addition thereto of a normally gaseous material under conditions which cause multitudinous extremely finelydivided bodies of said gaseous material to become uniformly dispersed throughout the slurry. The slurry, after the gaseous material is incorporated and intimately mixed therein, is removed from the mixing device and allowed to cool at ambient conditions whereby the product forms a solid which granulates or is capable of being readily transformed into a particulate detergent product having a low bulk density.

It is advantageous, in preparing a low bulk density product which is capable of retaining such low bulk density throughout the steps of cooling and other subsequent United States Patent 0 3,515,672 Patented June 2, 1970 treatment, to utilize a material which hydrates rapidly thereby imparting a relatively high structural strength to the detergent product. Suitable rapidly hydratable compounds include, for example, such materials as the alkali or alkaline earth metal trimetaphosphates which are capable of reaction with a strong base to form the corresponding alkali or alkaline earth metal tripolyphosphate hydrate.

In the practice of the invention, it is advantageous initially to form a premix of the slurry in the absence of any hydratable phosphate builder salt or other hydratable compound and then subsequently to incorporate the hydratable phosphate builder salt and the gaseous material with the premix at a time in the process immediately prior to passage of said premix into the mixing device. It has been found that by virtue of this initial formation of a premix there can be obtained, in a manner and for reasons set forth more fully hereinafter, a product issuing from the means for intimately mixing which has a higher solids content than could heretofore be obtained thereby reducing the necessity of removing large quantities of water from the final product. The reduction in moisture content of the final product thereby allows a reduction in capital and operating costs, such as by the use of smaller and more economical types of drying apparatus and correspondingly lower heat inputs.

This invention is particularly useful in the production of synthetic detergents from high solid feeds wherein it has heretofore been difiicult to obtain a sufiiciently low bulk density. Thus, the various novel steps and apparatus of this invention allow the production of a desirable low bulk density product of low phosphate content even though the material during processing possesses a high solids content.

Detergents which may be used in the process of the present invention are water soluble and organic in nature and in general should have foaming properties. Examples of suitable anionic detergents include the water soluble soaps and sulfonated synthetic detergents. The soaps are generally the water soluble salts of higher fatty acids (including rosin acids) which are derived usually from fats, oils and Waxes of animal, vegetable or marine origin, e.g., tallow, coconut oil, tall oil, palm kernel oil soaps and the like. It is preferred to employ a higher alkyl aryl sulfonate such as an alkyl benzene sulfonate detergent wherein the alkyl group has about 8 to 16 carbon atoms. Suitable examples are sodium decyl benzene sulfonate, sodium dodecyl and pentadecyl sulfonates wherein the dodecyl and pentadecyl groups are derived from a propylene polymer, sodium keryl benzene sulfonate, potassium dodecyl benzene sulfonate, and the like. Other suitable agents are the surface-active sulfated or sulfonated aliphatic compounds, preferably having 8 to 22 carbon atoms. Examples thereof are sulfuric acid esters of polyhydric alcohols incompletely esterified with higher fatty acids (e.g., sodium coconut oil monoglyceride monosulfate); the long-chain pure or mixed higher alkyl sulfates (e.g., sodium lauryl sulfate, sodium or potassium, coconut fatty alcohol sulfate, and sodium palm kernel oil alcohol sulfate); the higher fatty acid ethanolamide sulfates (e.g., sodium coconut fatty acid ethanolamide sulfate); the higher fatty acid amides of amino alkyl sulfonic acids (e.g., sodium lauric acid amide of taurine); the higher fatty acid esters of isethionic acid; and the like. These anionic surface-active agents are used generally in the form of their water soluble salts, such as the alkali metal (e.g., sodium, potassium), though other soluble salts such as ammonium, alkylolamine and alkaline earth metal salts may be used if desired depending upon the particular detergent.

In addition to the anionic detergents, the organic detergent may constitute in whole or in part a non-ionic detergent such as the non-ionic polyalkylene ovide condensates with an aliphatic or aromatic hydrophobic group. The hydrophobic organic group contains usually at least about 8 carbons condensed with at least about 5 and usually up to 50 alkylene oxide groups. Examples are the polyethylene oxide condensates With alkyl phenols having 6 to 20 carbons in the alkyl group such as Igepal CA and CO; the polyethylene oxide esters with higher fatty acids such as tall oil acids or lauric acid condensed with about 16 or 20 ethylene oxide groups; the polyethylene oxide condensates with higher aliphatic alcohols such as lauryl, myristyl, oleyl or stearyl alcohol with 6 to 30 moles ethylene oxide; the polyoxyethylene oxide condensates with higher fatty acid amides such as coconut fatty acid amide containing about to 50 moles ethylene oxide. The water soluble polyoxyethylene condensates with hydrophobic polyoxypropylene glycols may be employed also. Suitable non-ionic detergents may be, for example, the condensate of ethylene oxide with polypropylene glycol which condensate contains 80% ethylene oxide and has a molecular weight of about 1700, and iso-octyl phenoxy polyoxyethylene ethanol having about 8.5 ethanoxy groups per molecule, and the like.

A cationic surface-active agent may be incorporated in the product also. It may be admixed in powdered or liquid form with the ingredients in any suitable manner. Where it is desired to use a cationic agent, it is preferred to admix it in minor proportion with the acidic ingredent and coat this mixture with the coating agent. Suitable cationic detergents are the higher alkyl quaternary ammonium compounds such as the cetyl quaternary ammonium salts. Specific examples of such materials are cetyl trimethyl ammonium chloride, cetyl pyridinium chloride, and the like. Similarly, ampholytic detergents such as salts of the N-alkyl compounds of beta amino propionic acid wherein the alkyl group is derived from a fatty acid such as a mixture of coconut oil fatty acids such as sodium dodecyl beta-alarnine may be employed in compatible amounts.

The active detergent ingredient may in whole or in part be a higher fatty acid soap such as kettle soap. Such substitution facilitates the processing by imparting more rapid setting and aeration characteristics to the slurry. The soap itself lends some structural strength to the product and thereby reduces breakdown of the product particles. Suitable soaps include the water soluble alkali metal, amine, and ammonium salts of higher fatty acids, such as those containing from 10 to 18 carbon atoms, e.g. sodium laurate, sodium myristate, potassium palmitate, triethanolamine stearate, and mixtures thereof with each other and with soaps of unsaturated fatty acids such as sodium oleate (e.g. the sodium soap of tallow fatty acids and the sodium soap of an 85:15 mixture of tallow and coconut oil fatty acids).

A suitable range of proportions of the organic detergent is from about 2% to about 65% by weight of the finished product, and preferably about 10% to 40% thereof where the detergent is a synthetic material and about 2065% where a soap is the active material.

It is desirable to include in the formulation a small amount of a water soluble hydrotropic alkyl aryl sulfonate salt to aid in the successful entrainment of gas in the necessary quantity and finely divided form in the slurries employed in carrying out the instant process. As much as 20% of this material can be used; however, it has been found desirable to include in the formulation up to about 6% of the hydrotropic alkyl aryl sulfonate salt while up to about 2% is preferred. The alkyl aryl sulfonate salt used in carrying out the process may be a water soluble hydrotropic agent characterized by a hydrophile-lipophile balance such that they are highly water soluble in nature (more so, for example, than related organic detergents), and while they exhibit considerable surface activity, they are substantially non-detersive in nature. Examples of suitable hydrotropes are sodium toluene sulfonate, sodium xylene sulfonate, the sodium salt of dibutyl naphthalene sulfonate, sodium (mono-) dodecyl oxydibenzene disulfonate, and the corresponding potassium and lithium salts and mixtures thereof including commercially available isomeric: mixtures.

Preferably the alkyl substituent contains on the order of from 1 to 6 carbon atoms for each sulfonate group in the molecule, and the aryl nucleus desirably is benzene or naphthalene. The hydrotropic agent may be singly or plurally sulfonated or alkylated or both, and although reference has been made to alkali metal salts of these compounds, other water soluble salts such as the alkaline earth metal, e.g. magnesium salts and ammonium and substituted ammonium, e.g. the triethanolamine salts, may be used totally or partially in lieu thereof.

In operation, the lower alkyl aryl sulfonate salt may be added to the slurry as such, or it may be added in the form of the sulfonic acid and neutralized in the presence of other paste constituents. Likewise, the lower alkyl aryl sulfonic acid may be prepared by sulfonation of the appropriate hydrocarbon in the presence of other paste constituents if desired, as for example, by sulfonation with the same sulfonating agent usedto prepare other sulfated or sulfonated constituents of the paste, SIlChlflS a higher alkyl aryl sulfonate detergent. Such co-sulfonation may be either simultaneous or tandem as appropriate, it being preferred to sulfonate the lower alkyl aryl hydrocarbon as the last material to be sulfonated in the latter case.

An important feature of this invention resides in the provision of a material capable of reaction with water to produce a water soluble hydrate salt, preferably a polyphosphate hydrate salt. The formation of a hydrate of this type removes free water from the slurry and imparts structural strength to the finished product, thereby reducing or eliminating entirely break-down of the product as, for example, when under the Weight of superimposed material. Suitable hydratable compounds include alkali and alkaline earth metal phosphates such as pentasodium tripolyphosphate, both forms I and II, tetra-. sodium pyrophosphate, potassium pyrophosphate, trisodium orthophosphate, and sodium trimetaphosphate. Also suitable are such hydratable compounds as sodium carbonate, sodium metasilicate, magnesium sulfate, sodi-: um tetraborate, and the like and mixtures thereof. The hydratable material is used in particulate form. At least about percent of the particles will advantageously have a diameter smaller than about microns, and preferably at least about 97 percent of the particles have a diameter smaller than 150 microns while at least about, 85 percent thereof have a diameter smaller than about, 75 microns.

In determining the optimum hydratable compound to I be used in the formulation, it is preferred to use a rapidly hydratable compound. The faster the rate of hydration, the more quickly the structural strength will be increased thereby allowing the foraminous system to become self supporting. Accordingly, it is preferred that a compound be chosen which is capable of substantial hydration in less than about 30 minutes at the temperatures of the process. Suitably, a period of about 1-10 minutes is satis factory but a period of 2-5 minutes is preferred. Accordingly, a preferred hydratable compound is sodium trimetaphosphate, which, in the presence of a strong base, rapidly reacts to form sodium tripolyphosphate hexahydrate. Similarly, other alkali metal trimetaphosphates can be used to produce alkali metal tripoly hosphate Y hydrates. The hydratable material may be used in amounts of 20 to 80% by weight. The amount of hydrat- I able material will advantageously be about 30-50%, preferably, the hydratable material is an alkali metal trimetaphosphate which is utilized in the range of from about 30 to 50% by weight.

The conversion of trimetaphosphate to tripolyphosphate hydrate requires reaction with a strong base such as the alkali metal carbonates, silicates, oxides, hydroxides, orthophosphates, and alkaline earth metal oxides and hydroxides. The base should be sufficiently strong that it gives a pH in excess of about 10.2 at 25 C. when 1% by weight is dissolved in distilled water. The more desirable strong bases are the alkali metal hydroxides, carbonates, and silicates, and the sodium and potassium hydroxides are the preferred bases.

The strong base should be used in amounts sufficient to cause the desired conversion of the alkali metal trimetaphosphate into the corresponding alkali metal tripolyphosphate hydrate. Generally, the ratio of strong base to trimetaphosphate will be between about 1.421 to :1 and preferably from about 2:1 to 6:1 mole equiva lents. The exact amount will depend upon the particular base and trimetaphosphates to be used.

It may be desirable to include in the formulation certain compounds in addition to those set forth above which compounds may be useful for various purposes such as fillers, i.e. sodium sulfate, anti-redeposition agents, i.e. carboxymethyl cellulose, buffers, brighteners, colorants, stabilizers, and the like.

The water content of the slurry during the high shear mixing step is generally less than that at which the material can readily be pumped or flowed through a conduit without some difiiculty. This is accomplished by initially forming a premix which contains all or a major portion of the water and a portion only of the solids, and commingling the remainder of the solids therewith just before the high shear mixing. The total solids content of the slurry employed in carrying out the process of the present invention at the time it is mixed in the high shear mixing device may vary from about 70 to 85% of the total composition, depending upon the other constituents present and the processing conditions employed. A preferred range for the solids content is from about 75 to 80%. In any event, enough Water must be used so that the slurry after the intensive mixing step is of such viscosity and fluidity that it forms a uniform paste having a consistency which permits it to swell or expand but which prevents rise of gas through the paste and therefore substantially preserves a structure of thoroughly dispersed discrete gaseous bodies, preventing substantial coalescence of the gaseous bodies or loss of gas from the system.

The gaseous material of this invention which is intimately admixed with the slurry to form voids therein may be any suitable normally gaseous material such as air, nitrogen, oxygen, carbon dioxide and the like. It is preferred, however, to use an inert, normally gaseous material such as air.

The present process is advantageous in that it produces a product of low apparent density and high rate and degree of solubility in water. When granulated, the particulate products produced exhibit little tendency towards dust formation or caking during transportation and/or storage, and excellent odor characteristics compared with products made from comparable materials in accordance with presently employed commercial procedures. Moreover, in contrast to many relatively high temperature heat dried detergent compositions, the instant products have a negligible content of products of thermal degradation or organic or inorganic constituents and thus are, when made from water soluble materials, completely water soluble.

In the presently contemplated continuous operation, wherein a premix is formed and continuously fed to a mixing device, and an additive such as trimetaphosphate in combination with a strong base is continuously added just prior to the high energy mixing step set forth in detail hereinafter, it is particularly desirable to provide a continuous metered flow of the premix and additive streams to allow continuous and exact proportioning of the components. In one embodiment of the system presently contemplated for producing detergent material wherein the use of high solids is envisioned, thereby causing the material to be diflicultly flowable, it is important to be able to rapidly adjust the relative proportions of the component streams to obtain a uniform product. The system described herein provides for a weight control operation which responds instantaneously and accurately whereby a uniform product can be obtained.

This invention contemplates the use of a plurality of metering devices each employing two receptacles, for reasons discussed more fully below, whereby continuous weighing and control of the rates of flow of the components can be obtained. These units are especially commercially desirable in plants having a capacity in excess of 1500 pounds per hour since, in plants of that capacity, such units will enable more accurate and less costly control of the process at high solids contents. One aspect of this invention, therefore, relates to a method and apparatus for accurately measuring and controlling the weight rates of flow of the premix slurry and the materials added thereto just before mixing, primarily the hydratable material. The control system employs an intermittent receptacle and a continuous receptacle for each stream to be controlled, Series connections for each stream are maintained between the receptacles and each source of supply and the processing equipment. Means are provided for continuously weighing the contents of the continuous receptacle and for continuously weighing the combined contents of both receptacles and translating this into control signals in terms of instantaneous rate of change of Weight independent of the actual weight itself. The control system further includes means for providing a continuous predetermined rate of change command signal independent of the time reference and for comparing it with one or both of the foregoing instantaneous rate of change of weight signals for controlling discharge of the streams of material from the continuous receptacle thereby reducing to zero the differences between those signals being compared. The signals for each stream are also compared, and the relative rates of feed controlled in relation thereto.

As discussed hereinabove, certain materials should be added immediately prior to the high power-input mixing step. This is especially important where a degradable or hydratable material such as sodium tripolyphosphate or sodium trimetaphosphate is used and reactions immediately begin to occur. For example, sodium tripolyphosphate is subject both to hydration and hydrolysis. When hydration occurs water is removed from the mixture. When working at the high solids concentration of this invention, hydration causes the slurry to become even less fluid so that it cannot be flowed or adequately mixed. Other reactions such as hydrolysis caused degradation of the material resulting in an undesirable final product. Accordingly, it is necessary to minimize both the hold-up time and the mixing time. It is therefore preferred that the premix slurry and the additive material remain in the feeders for as short a period of time as possible. The time after all of the components of the final product have been commingled and before the high shear mixing is begun is suitably maintained at about five seconds or even less. The throughput time in the high shear mixer will advantageously be less than about 30 seconds, and preferably between about five and 20 seconds. The preferred control system of this invention has the ability accurately to combine a plurality of ingredients in a minimum of time whereby the relative proportions of ingredients can be adjusted in accordance with an instantaneously responsive control mechanism that measures the rate of feed of each of the component streams, immediately compensates for variations in rate change or component demand and is capable of carrying out all of these necessary functions with a total hold-up time of less than about five minutes. Thus, the combination of an intermittent receptacle and a continuous receptacle in a manner described more fully hereinafter in combination with a high solids feed of detergent component streams results in a flexible system capable of deriving a high quality product with a minimum of undesirable side products.

Various objects and advantages will be apparent from the following description of the invention and the novel features to :be particularly pointed out hereinafter in connection with the appended claims.

In the accompanying drawing, FIG. 1 is a partially schematic flow diagram showing one embodiment of the invention.

The means for measuring and controlling the weight rates of flow of the premix slurry and the materials added just :before mixing comprises two units, a first unit for the measurement and control of the premix slurry and a second unit 110 for the measurement and control of the additive materials. These units may be similar in apparatus and function. The first unit 10 comprises two vertically aligned material receiving receptacles 21 and 22 that are preferably about the same size and are mounted in cooperative relation upon a stationary structural support 23.

Upper receptacle 21 is of any suitable shape and may, for example, be conically formed with an inlet conduit 24 constantly connected to supply premix slurry through its normally covered larger upper end. A supply valve (not shown) is provided in conduit 24. The lower end of upper receptacle 21 is connected to discharge into a conduit 25 through transfer valve 26. Conduit 25 enters the upper end of lower receptacle 22 and discharge from receptacle 22 is effected through a conduit 27 controlled by an adjustable orifice flow metering valve 28, or other suitable valve means. Conduit 25 positioned between the upper and lower receptacles 21, 22 is adapted to permit relative movement between upper and lower receptacles. This may be accomplished by the provision of longitudinally slidable collar means 29 or other suitable means such as by pressure of a longitudinally flexible conduit.

A suitable horizontal mounting frame 31 is provided to support upper receptacle 21 and may be secured thereto by welding or bolting as to brackets 37, 37. Mounting frame 31 is supported by hangers 41, 41 which extend downwardly from support bars 42, 42 and are pivotally connected thereto inwardly of fulcrums 46, 46' at which point support bars 42, 42 are pivotally attached to depending members 48, 48' which extend downwardly from structural support 23. At their innermost ends, support bars 42, 42 are connected to loading members 53, 53' which at their uppermost ends are connected at 54 on load cell 55 of a suitable type that is mounted on the upper part of structural support 23. Load cell 55 may be, for example, an electric strain gauge having its output amplified.

Extensions 59, 59' of hanging members 41, 41' extend downwardly and support a horizontal frame member 61. A horizontal mounting frame 63 similar to mounting frame 31 is provided for the lower receptacle 22 and is rigidly secured thereto as by welding or bolting to brackets 64, 64' on receptacle 22. Mounting frame 63 is supported by hangers 65, 65' which extend downwardly from support bars 71, 71' and are pivotally connected thereto inwardly of fulcrums 73, 73 at which point support bars 71, 71' are pivotally attached to depending members 59, 59' which extend below horizontal support 61 in the manner shown. At their innermost ends, support bars 71, 71 are connected to loading members 75, 75 which at their upper ends are connected at 77 on load cell 79 of a suitable type, which is mounted on support 61. Thus, lower receptacle 22 is directly suspended from upper receptacle 21 and load cell 79 measures the weight of lower receptacle 22 and its contents while load cell 55 measures the combined weights of both receptacles and their contents.

8 The second unit for the measurementand control of rate of feed of the additive material is similar to the first unit 10 for control of the premix slurry and comprises two vertically aligned receptacles 121 and 122 mounted in cooperative relationship on structural support 23. Upper receptacle 121 is provided with an inlet conduit 124, connected to supply additive material thereto. Feed to receptacle 121 through conduit 124 is controlled by a suitable valve (not shown). Receptacle 121 is connected 5 through conduit 125 to lower receptacle 122, and conduit 125 is provided with transfer valve 126. Conduit 125. between receptacles 121 and 122 is adapted to permit relative movement between these receptacles. This may be accomplished by provision of collar means 129 or other suitable means.

Mounting frame 131 is provided to support upper receptacle 121 and may be secured thereto by suitable means such as brackets 137, 137. Frame 131 is supported by hangers 141, 141' which extend downwardly from support bars 142, 142. Hangers 141, 141lare pivotally connected to support bars 142, 142 inwardly of fulcrums 146, 146 at which point support bars 142,1 142 are pivotally attached to depending members 148, 148' which are attached to and extend downwardly from structural supports 23. At their innermost ends, support bars 142,.

142 are connected to loading members 153, 153' which at their uppermost ends are connected at 154 on load cell 155 of a suitable type that is mounted on the upper. part of support 23.

Hanging members 141, 141' are extended beyond frame 131 and these extensions 159, 159 support a horizontal frame member 161. A horizontal mounting frame which at their upper ends are connected at 177 on load 1 cell 179 which is mounted on support member 161. In a manner that will be readily understood, lower receptacle 122 is suspended from upper receptacle 121 whereby load cell 179 measures the weight of lower receptacle 122 1 while load cell 155 measures the combined weights of both receptacles.

For purposes of understanding the operation of the measuring and controlling apparatus, receptacle 21 will be referred to as the first intermittent receptacle and receptacle 22 will be referred to as the first continuous receptacle. Similarly, the upper receptacle 121 for the additive material will be referred to as the second intermittent receptacle and receptacle 122 will be referred to as the second continuous receptacle. As used throughout the specification and claims the term intermittent receptacle refers to a receptacle in the disclosed system which is adapted to discharge material intermittently therefrom, and the term continuous receptacle refers to a receptacle in the disclosed system which is adapted to discharge material continuously therefrom.

In operation, with suitable tare adjustments having been made and with the first and second continuous receptacles 21, 121 empty, the weights of the contents of receptacles 22, 122 are continuously measured by load cells 79, 179.

Discharge of material from receptacles 22, 122 into feeder 200 is initiated through conduit means 202, 204 by automatically opening flow metering valves 28, 128

vantageously, feeder 201) comprises an open-throat pro- 7 gressing cavity pump such as a Moyno pump. It is also contemplated that the material from receptacles 22 and 122 be fed into separate positive feed devices in which case the streams of material are combined just prior to charging of the material into the high shear mixing device.

The weights of the contents of first and second continuous receptacles 22, 122 are continuously measured by load cells 79, 179 which are connected into circuits designated at 81, 181 that provide on leads 82, 182 electrical output signal potentials that are functions of the instantaneous rates of change of weight of the contents of receptacles 22, 122 respectively. The value of these signals is thus independent of the amount of weight of the c ntents of each of continuous receptacles 22, 122. The control section of the system of the invention includes separately energized command signal generators 83, 183 that produce on leads 84, 184 electrical signal potentials which may be adjusted as at 85, 185 to produce signals corresponding to different rates of change of weight of the contents of receptacles 22, 122. The adjustments at 85, 185 are calibrated to the rates of flow through valves 28, 128 respectively. The measured signal potentials on leads 82, 182 are compared to the command signals on 84, 184 respectively as by a potentiometer arrangement Within self-balancing comparators designated 86, 186 and the outputs of comparators 86, 186 are connected by leads 80, 180 to servomotor devices 87, 187 respectively which are connected to vary the size of the flow orifices in valves 28, 128 when actuated. Thus, depending upon the settings at 85, 185, the premix slurry from first continuous receptacle 22 and the additive materials discharging from second continuous receptacle 122 discharge through conduits 27, 127 at controlled predetermined rates representing a controlled rate of change of weight of the contents of first and second continuous receptacles 22, 122.

The automatic control for system for the premix slurry as operated during refilling of the first continuous receptacle operates in the following manner. At a predetermined time prior to complete discharge of all contents from first continuous receptacle 22 the intermittent receptacle 21 is quickly filled with premix slurry by opening the supply valve (not shown) in conduit 24 and then closing said valve to cut off further supply of premix slurry when the first intermittent receptacle 21 reaches a predetermined level. First intermittent receptacle 21 will preferably be filled with enough material to fill first continuous receptacle 22. During the filling of first intermittent receptacle 21 and at all times throughout the operation of the process, the first continuous receptacle 22 continuously discharges material at a controlled rate. After first intermittent receptacle 21 is filled, and the valve in conduit 24 is closed, the weight of the combined contents of both receptacles 21 and 22 is then continuously measured by load cell 55 which is connected into circuit 91 thereby producing on lead 92 an electrical output signal potential that is a function of the instantaneous rate of change of weight of the contents of the combined receptacles 21 and 22. This instantaneous change of weight of the combined receptacles is, of course, the same as the instantaneous rate of change of weight of lower continuous receptacle 22 alone. This is true because continuous receptacle 22 continues to discharge from the system a certain number of weight units per unit of time at the same controlled rate as previously. Accordingly, the measured signal potential on lead 92 equals that on lead 82.

After the first intermittent receptacle 21 has been filled and before the first continuous receptacle 22 is emptied, the switching device 93 is automatically operated to quickly substitute the measured signal potential of lead 92 for that of lead 82 at the comparator 86 so that the comparator is comparing the measured signal potential corresponding to change in weight of the combined receptacles to the command signal of generator 83 to control the orifice of metering valve 28. The rate of discharge of the fluent material into the process after the switching device 93 has automatically substituted the potential of lead 92 for that of 82 does not change for the reasons set forth above. Next, the transfer valve 26 between the first intermittent receptacle and the first continuous receptacle is opened to quickly discharge the contents of the first intermittent receptacle 21 into the first continuous receptacle 22 after which valve 26 is closed. This operation does not change the controlled rate of change of the weight of the premix slurry since control of the orifice of flow metering valve 28 and therefore the weight rate of discharge of the fluent material is continuously maintained and controlled in relation to the change in weight of the first intermittent and continuous receptacles combined. After closing transfer valve 26, the switching device 93 is automatically actuated to substitute the measured signal potential of lead 82 for that of 92 by virtue of lead 94 and whereby the load cell 79 again supplied the measured weight control as at the start. At this time, the first intermittent receptacle 21 can again be quickly refilled without affecting the weight rate control of discharge of the contents of first continuous receptacle 22 and the foregoing cycle of operation repeated throughout operation of the process.

The operation of the measuring and controlling system 110 for the additive material during changing of the feed system, comprised of second intermittent receptacle 121 and second continuous receptacle 122, operates in the same manner as that described immediately above with reference to the system 10 for controlling the premix slurry and will not be described in detail. It is understood that the control system 110 for the additive material is adjusted to a feed rate as may be predetermined to be desirable in relation to the feed rate of the premix slurry. It is desirable to closely control the ratio of premix slurry to additive material. Accordingly, the feeder 200 may be operated in the nature of a valve for the premix slurry in lieu of the use of valve 28. In such embodiment, the signal of line may be used to control the speed of variable speed motor 206 which actuates the shaft 208 of the worm 210 of feeder 200 and the valve 28 is eliminated thereby allowing the premix slurry to be metered from the first continuous receptacle 22 by screw feeder 200.

Since it is of importance to closely control the ratio between the premix slurry and the additive materials there is additionally provided a master controller 212 which compares the signals from comparators 86, and 186 which signals represent the rate of flow of premix slurry and additive material respectively, master controller 212, is calibrated in accordance with a predetermined desired ratio and resets either of the controllers 86, 186 or both to maintain the rates of flow of premix slurry and additive material in accordance With the predetermined ratio. Thus, two different streams are continuously supplied in accu rately metered flow to a common point of addition. Master controller 212 and comparators 86, 186 can be reset manually to adjust the rates of feed and the ratios thereof relative to each other. Thus, the mixture proportions may be accurately set and maintained at all times and a correct formulation of the premix slurry and the additive material is maintained even Where demand or rate of flow of either material varies. The control system, because of its instantaneous response allows production of a high quality, uniform product.

The high solids content mixture of premix slurry and additive materials is substantially immediately, i.e. within about five seconds, passed through conduits 220, 240 to high shear mixing device 222. A feed line 224 is positioned to inject a gaseous material into the mixture in conduit 240 before the mixture enters the high shear mixer 222. The gaseous material is fed under pressure through conduit 224 by variable pump means 226 the inlet of which is connected by conduit 227 to a source of supply for said gaseous material. Means 225 is provided for injecting the gaseous material into the flowing stream in conduit 240. Means 225 advantageously comprises a short length of metal tubing disposed in a direction normal to the flow in conduit 240. The metal tubing is provided with two diametrically opposite pinholes and the tubing adjacent the pinholes is surrounded by a flexible rubber member which fits over the pinholes. As gaseous material under pressure is fed through feed conduit 224 it forces the flexible member away from the metal tubing thereby allowing the gaseous material to discharge into conduit 240. When the flow of gaseous material is terminated, the flexible member covers the pinholes thereby eliminating any possibility of clogging thereof by back pressure from the mixture flowing in conduit 240.

Another feed line 228 is provided for use when an additional component is to be added such as the caustic required when an alkali metal trimetaphosphate is the hydratable material. Conduit 228 is fed from a metered source (not shown) which may be of any suitable type. Where an alkali metal trimetaphosphate is to be added and line 228 is connected to supply a caustic solution, the reaction between the hydratable material and the water present in the premix slurry is not initiated until the trimetaphosphate is brought into the presence of the caustic. In such instance, the material does not form substantial amounts of hydrate until the caustic is added. Thus, all or a part of the trimetaphosphate may be incorporated into the premix slurry earlier than otherwise possible. This may be accomplished, for example, by discharging from both receptacles 22 and 122 into conduit 202 at the intake end of feeder 200. The exact point or time of addition of the hydratable material to the premix slurry depends upon the many variables and operating parameters such as the rate at which the hydration occurs, the temperatures involved, the solids content, the relative amounts of the compounds, etc.

The mixing device 222 for intimately and continuously mixing the formulation and evenly dispersing the gaseous material therein as finely divided, substantially uniform, small bodies must impart a high shear to the mixture. Suitable mixers are generally relatively small in capacity so that at any particular moment only a small quantity of slurry is being worked upon thereby allowing a major portion of the power input to be used directly on the slurry without becoming dissipated in an attempt to mix large quantities of material at one time. Thus, the mixer 222 will advantageously have a capacity of less than about one gallon whereby material can be passed through the mixer in less than about 30' seconds after being subjected to extremely high shear for this short period of time. The mixing device may be of any suitable structure and, for example, may advantageously comprise a mixing chamber 230 having two stators 232, 234 and a rotor 236 adapted to rotate between the stators. The internal faces of both of the stators and both faces of the rotor may be provided with concentric rows of blades 238 arranged so that the blades of the rotor 236 mesh closely but out of contact with the blades of the stators 232, 234. The slurry may advantageously pass from an inlet 240 at the center of one stator, between the blades of that stator and the rotor, across the rotor, and between the blades of the other stator and the rotor, and then to an exit 242 at the far end of the mixer. In traversing this course through the mixing device the slurry and the gaseous material are torn, stretched, and cut by the blades into countless streams, and minute bodies of the gaseous material are evenly distributed throughout the slurry. Other types of mixing devices may be used so long as the device is capable of imparting large quantities of energy and high shear rates to the slurry whereby a majority (i.e. greater than 50 percent) of the gaseous material is broken into discrete gaseous bodies having an average diameter on the order 12 of less than about 0.085 millimeter and preferably less than about 0.05 4 millimeter.

Shear as used herein refers to an action resulting from applied forces which action causes contiguous portions of the mixture being treated to slide relative to each other. The forces applied to the mixture vary with the equipment used and the operating parameters of the process. By high shear is meant an action-of the type set forth immediately above wherein there is a Shear Factor (F) as defined below in excess of about five and preferably in excess of about 6.5.

whe rein r=the radius of the mixer rotor in inches or its equivalent for a diflferent type of mixing device;

R=the number of revolutions of the mixer rotor per minute or its equivalent;

T the rate of feed of the material to be sheared in pounds per hour;

d=the clearance between the blades on the rotor and those on the stator or its equivalent; and

C=the volumetric capacity of the mixing device in cubic inches.

Tubular member 244 is provided at the outlet 242 .of mixer 222 for transfer of the intimately mixed material from the mixer to conveying means 250. The tubular member 244 is used to adjust the internal pressure in mixer 222 and therefore may vary in length and diameter. For example, by increasing the length or decreasing the diameter of member 244, the pressure within mixer 222 can be increased. It is desirable to use a pressure controlling member of this type instead of a throttle valve to avoid a sudden drop in pressure which may cause instability of the product. The length and diameter of the tube may be changed to maintain the mixer pressure within the range of about 20 to pounds per square inch gauge and preferably within about 40 to 65 pounds per square inch gauge. Advantageously, the length of the tube will be at least ten times the equivalent diameter thereof.

The detergent product is discharged from member 244 onto conveying means 250 which advantageously comprises a continuously moving belt whereby the product may be rapidly removed, thereby eliminating piling up of product to an undesirable height which might tend to break down the structure of the product causing the final bulk density to be higher than desired. It may be desirable to maintain the temperature of the product on belt 250 at a predetermined level for a predetermined time in which. instance continuous conveyor 250 may be provided with;

means 252 to heat and/ or cool selectively. Means 252 is shown as a chamber; however, equivalent equipment suchz as a thermostatically controlled electrical resistance heater may be used. Means may also be provided, if necessary, for breaking the product into particles or for breaking apart lumps of product in the event that such are pro-.

duced. Product from conveyor 250 is discharged onto a transfer conveyor 254 which feeds the product into drying means 256 which, in the embodiment shown, is in the nature of a rotary kiln dryer but which may comprise any suitable drying device. Thus, dryer 256 may comprise a fluidized bed heating chamber, a continuous belt which passes through a heating tunnel, a spray drying tower, a'vertical shaft heating chamber, and the like. For reasons of economy, however, it is preferred that a tumbling drum type of dryer of the type illustrated be used. Especially economical drying is made possible by virtue of the low free moisture content of the product. The final product issuing from drying means 256 is passedto suitable removal means 258 which delivers the material to storage, packaging, or other desired location. Perfumemay be added to the product at any suitable time as at the end of the drying step.

13 The following specific examples are illustrative of the nature of the invention but it is to be understood that the invention is not limited thereto. Unless otherwise indicated, all parts, proportions, and percentages throughout the specification, examples, and claims are by weight and all inorganic salts are anhydrous.

EXAMPLE I Open throat progressing cavity feeder 200 is continuously fed with two streams of material. One stream consists of a slurry made from the following materials:

The slurry constituting the first stream is maintained at a temperature of about 57 C. and is delivered to the progressing cavity feeder 200 from receptacle 2.2 of metering device at the rate of 304 pounds per hour. The second stream consists of Form II powdered pentasodium tripolyphosphate delivered from receptacle 122 of metering device 110 at a rate of 161 pounds per hour. Form II pentasodium tripolyphosphate is a phosphate which during manufacture is calcined at a low tempera ture as compared to Form I which is calcined at a higher temperature. Form I pentasodium tripolyphosphate hytains an operating pressure of about pounds per square inch gauge at the inlet of the mixer, and provides for a gradual diminution of the pressure on the material being processed.

Discharge from the high shear mixer is a uniformly mixed and aerated paste with a density of about 0.44 gram per cubic centimeter at a temperature of about C. It is fed into a series of tubes, where it is allowed to remain in a quiescent state at room temperature for about 48 hours. During this period it solidifies. The product is removed from the tubs and passed through a rotating cage mill to reduce all lumps present to small particles and is then screened through a sieve having square apertures 2 millimeters on a side. The resulting powder has an apparent density of 0.38 gram per cubic centimeter and a moisture content of about 22%, and is dried to 18 percent total moisture in a moving current of warm (60 C.) air. This product has a composition approximately as follows:

Percent Tridecylbenzene sodium sulfonate 25 Pentasodium tripolyphosphate 37 Sodium toluene sulfonate 2 Sodium silicate 6 Sodium carboxymethyl cellulose 0.8

Sodium sulfate 11 Water (essentially all molecularly bound by the phosphate and other hydratable salts) 18 EXAMPLES II-VIII A series of experiments are carried out under varying operating conditions and with a composition having the same formulation as that described in Example I unless otherwise indicated. The operating conditions are set drates more rapidly than Form II thereof. The Form II 35 forth in Table I below:

TABLE I Air Rotor Temp. of Solids (standard speed of Prod." premix Feed content cubic feet mixer Prod. mois. slurry 1 rate 2 (percent) 3 per hour) 4 (r.p.m.) 5 Pressure Temp. dens. 8 (percent) factor STS 1 1 This temperature is measured in degrees Fahrenheit at hopper 202. 2 The feed rate is calculated in pounds per hour.

3 The solids content is calculated as including all components and without any hydration.

4 Standard cubic feet is calculated at a pressure of 760 millimeters mercury and a temperature of 0 degrees centigrade.

5 The rotor has a diameter of eight inches. The mixer has a capacity of 70 cubic inches, and the clearance between the blades of rotor and stator is 0.060 inch.

pentasodium tripolyphosphate used in this example is comprised of particles of which 86 percent thereof are less than 75 microns in diameter, and 11 percent have a diameter between 75 and microns.

The mixture of powder and slurry is subjected to some preliminary mixing before discharge from feeder 200, and the material discharged from feeder 200 comprises a mixture of powder and slurry in a substantially constant ratio. The solids content of the material at this point is 77 percent.

The speed of the progressing cavity feeder is set to maintain a constant, low level in its feed hopper. The feed is pumped through conduit 220 directly to continuous high shear mixer 2 22 of the type shown and described herein. Holdup time in transfer conduit 220 amounts to about thirty seconds. Immediately upstream of the mixer a metered stream of compressed air is introduced into the paste, and the mixture enters mixer 222 within about five seconds thereof. This air amounts to about 4.0 standard cubic feet of air per hour. The mixer is operated at a rotor speed of 400 rpm. A 14-inch length of one-half inch inside diameter tubing on the mixer discharge main- 6 The pressure is measured in pounds per square inch gauge at the inlet of the high shear mixer.

7 This temperature is measured in degrees Fahrenheit at the inlet of the high shear mixer.

B The product density is measured in grams per cubic centimeter. Product moisture.

The amount oi sodium toluene sulfonate in the final product expressed as percent by weight.

In Example IV Form I pentasodium tripolyphosphate is substituted for the Form II pentasodium tripolyphosphate used in the other examples. The Form I compound hydrates more rapidly than Form II pentasodium tripolyphosphate. A comparison of Example IV with similar Example III which uses Form II pentasodium tripolyphosphate shows the improvement possible through use of a more rapidly hydratable material to impart structural strength to the product as it leaves the high shear mixing device. Example V illustrates another instance in which a Form I pentasodium tripolyphosphate is substituted for the Form 11 content.

As a comparison to the examples of the invention set forth above, Run A is performed wherein the entire formulation is made up in a batching device and the hydratable material, Form II pentadsodium tripolyphosphate, is included in this batch instead of being added later in the processing *as in the other examples. The completely formulated material is fed by feeder 200 to high shear mixing device 22 2. During the course of a half hour run, the mix becomes too thick to pump due to substantial hydration of the hydratable material.

Percent Water 27.77 50 B. caustic soda solution 12.6

Sodium toluene sulfate (powdered commercial grade) 3.0 Tridecylbenzene sulfonic acid 49.7 Form II pentasodium tripolyphosphate 6.6

The slurry constituting the first stream is maintained 1 6 between 73.5 and 79.0 percent. A second stream com prising powdered sodium trimetaphosphate having an average particle size less than about 75 microns is metered to feeder 200 at the rate of 154 pounds per hour. The feeder 200 pumps the mixture directly to continuous high shear mixer 222. Immediately upstream of mixer 222, 1a 50 B. caustic soda solution is metered into conduit 220 at the rate of 60 pounds per hour and air is metered into the conduit at the rate shown in Table II. The product resulting from each of these examples is a low density detergent of uniform consistency having density and moisture contents as shown in Table II. This material may be furtherdried in any suitable manner to an even lower moisture content. 1

TABLE 11 Air Rotor Solids (standard speed of Prod. Feed content cubic feet mixer Prod. mois. Shear rate 2 (percent) 3 per hour) 4 (r.p.m.) 5 Pressure 4 Temp. dens. 8 (percent) factor STS 1 This temperature is measured in degrees Fahrenheit at hopper 202.

2 The feed rate is calculated in pounds er hour.

3 The solids content is calculated as ncluding all components and without any hydration.

4 Standard cubic feet is calculated at a pressure of 760 millimeters mercury and a temperature of 0 degrees centigrade.

5 The rotor has a diameter of eight inches. The mixer has a capacity of 79 cubic inches, and the clearance between the blades of rotor and stator 18 0.060 inch. at a temperature of about 155 F. and is delivered to feeder 200 at the rate of 188 parts by weight per hour. A second stream comprising 178 parts by weight per hour of anhydrous sodium sulfate as filler is delivered to feeder 200 and therein combined with the initial slurry.

The feed is pumped to a high shear mixing device under approximately the same conditions as those described in Example I and about 3.4 standard cubic feet per hour of air is introduced. A pressure of about 40 pounds per square inch gauge is maintained at the inlet to the mixer. The product discharged from the mixer is a wet paste and fails to form a suitable product even though a lesser amount of water is used than in the examples set forth above. The cause of this is determined to be lack of sufficient hydratable material to bind the water, thereby providing inadequate structural strength. In addition, difliculty is found in feeding the slurry due to the initial incorporation in the slurry of the hydratable material.

EXAMPLES IX-XV In this series of examples, the hydratable material is sodium trimetaphosphate and the examples are carried out in the following manner:

Feeder 200 is continuously fed with two metered streams of material. A first stream comprises a slurry of the following:

Parts by weigh Sodium toluene sulfonate 3.1 Sodium tridecylbenzene sulfonate (54% solids, 46% water; 86% active ingredient, 14% inert ingredient) 31.0 Sodium silicate solution (43.5% solids, 56.5%

water) 14.0 Kettle soap (sodium salt of a mixture of fatty acids derived from tallow and coconut oils in the weight ratio of 80:20 respectively) 7.0 Sodium carboxymethyl cellulose (74% active ingredient, 26% inert ingredient) 0.8 Powdered polyvinyl alcohol 0.3 Ultra-marine blue 0.3 Sodium sulfate powder 43.5

The premix slurry constituting the first stream is maintained at a temperature of about 150 F. and is delivered to feeder 200 at a rate of 250 pounds per hour. The solids content of the premix slurry for Examples IX-XV varies a The pressure is measured in pounds per square inch gauge at the inlet of the high shear mixer.

1 This temperature is measured in degrees Fahrenheit at the outlet of the high shear mixer.

5 The product density is measured in grams per'cubic centimeter.

9 Product moisture.

The amount of sodium toluene sultonate in the final product expressed as percent by weight.

The product densities shown in Table II illustrate an 1 advantage of the present process which enables the preparation of a product having a bulk density lower than 0.35 even though the processing conditions included the i use of a solids content higher than percent, and also notwithstanding the fact that the final product contains less than 35 percent by Weight of tripolyphosphate which is a relatively low tripolyphosphate content for low bulk respectively.

Although the present invention has been described and illustrated with reference to certain specific examples, it is I understood that modifications and variations are contemplated within the scope of the appended claims.

What is claimed is: 4

1. Apparatus-for the production of low. density detergents wherein a premix slurry is formulated and intimately mixed with at least one additive material, wherein the relative proportions of the components are maintained substantially constant, and wherein. at least one of said components has a high solids content thereby causing said component to be difficultly flowable comprising; in combination a first control system for metering the continuous flow rate of the component having a high solids content from a supply to a point of addition of the additive material and a second control system tocontinuously meter the continuous flow rate of the other component to said point of addition, means to intimately mix said'ingr'edi- I cuts and means to remove water from the intimately mixed mixture thereby forming an apparently dry detergent product, said first control system comprising a support, a first weighing unit mounted on said support, an inter-.

mittent receptacle suspended from said first :weighing unit, means connecting said intermittentrreceptacle to a supply of fluent material, a second weighing unit carriedby said intermittent receptacle, a continuous receptacle suspended from said second weighing unit,;meansdefining a passage between said receptacles, a transfer valve in said pas sage, metering means providing controlled continuous discharge of said material from saidcontinuous receptacle, and means for cyclically connecting said first and second weighing units to a control unit to continuously con trol said metering means, and means to compare the ratesv of flow of said components as measured by said first and second control systems and to adjust said rates of flow relative to each other in accordance with variations in either to conform to a predetermined ratio therebetween.

2. The apparatus of claim 1 wherein said means to re move water comprises a rotary drying kiln.

3. The apparatus of claim 1 wherein said means to remove water comprises a spray drying tower.

4. The apparatus of claim 1 wherein said means to remove water comprises a fluid bed drying chamber.

5. Apparatus for the production of low density detergents wherein a premix slurry is formulated and intimately mixed with at least one addition material, wherein it is essential that the relative proportions of the components be maintained substantially constant, and wherein at least one of said components has a high solids content thereby causing said component to be diflicultly flowable comprising; in combination a first control system for metering the continuous flow rate of the component having a high solids content from a supply to a point of addition of the additive material and a second control system to continuously meter the continuous flow rate of the other component to said point of addition, means to intimately mix said ingredients and means to remove water from the intimately mixed mixture thereby forming a substantially dry detergent product, said first control system comprising a support, a first weighing unit mounted on said support, a first intermittent receptacle suspended from said first weighing unit, means connecting said first intermittent receptacle to a supply of fluent material, a second weighing unit carried by said first intermittent receptacle, a first continuous receptacle suspended from said second weighing unit, means defining a passage between said receptacles, a transfer valve in said passage, metering means providing controlled continuous discharge of said material from said first continuous receptacle, and means for cyclically connecting said first and second weighing units to continuously control said metering means, said second control system comprising a support, a third weighing unit mounted on said support, a second intermittent receptacle suspended from said third weighing unit, means connecting said second intermittent receptacle to a supply of material, a fourth weighing unit carried by said second intermittent receptacle, a second continuous receptacle suspended from said fourth weighing unit, means defining a passage between said second intermittent receptacle and said second continuous receptacle having a transfer valve therein, second metering means providing controlled continuous discharge of material from said second continuous receptacle and means for cyclically connecting said third and fourth weighing units to a control unit to continuously control said second metering means, and means to compare the rates of flow of said components as measured by said first and second control systems and to adjust said rates of flow relative to each other in accordance with variations in either.

6. The apparatus of claim 5 wherein said means to remove water comprises a rotary kiln.

7. The apparatus of claim 5 wherein said means to remove water comprises a spray drying tower.

8. The apparatus of claim 5 wherein said means to remove water comprises a fluid bed drying chamber.

9. The apparatus of claim 5 wherein said means to intimately mix comprises an enclosed casing, a rotor positioned within said casing, a plurality of blades aflixed to said casing and extending towards said rotor, a plurality of blades afiixed to said rotor and extending towards said casing, said blades affixed to said rotor adapted, upon rotation of said rotor, to pass between the blades aflixed to said casing, means to feed material to said casing, means to remove material from said casing, and means to rotate said rotor whereby said blades intimately mix said material during its passage through said casing.

10. Apparatus for the production of low bulk density detergents wherein a premix slurry is formulated and intimately mixed with at least one other material, wherein the relative proportions of the components are maintained substantially constant, and wherein at least one of said components has a high solids content thereby causing said component to be difficultly flowable comprising; in combination a control system for metering the rate of continuous flow of one component from a supply to a point of addition of the other material, means to continuously flow the other component to said point of addition, means to continuously determine the rate of flow of said other component, means to intimately mix said ingredients, and means to remove water from the intimately mixed mixture, said control system comprising a support, a first weighing unit mounted on said support, an intermittent receptacle suspended from said first weighing unit, means connecting said intermittent receptacle to a supply of fluent material, a second Weighing unit carried by said intermittent receptacle, a continuous receptacle suspended from said second weighing unit, means defining a passage between said receptacles, a transfer valve in said passage, metering means providing controlled continuous discharge of said material from said continuous receptacle, and means for cyclically connecting said first and second weighing units to a control unit to continuously control said metering means, and means to compare the rates of flow of said components to adjust said rates of flow relative to each other in accordance with variations in either.

11. Method for the production of low bulk density detergents comprising; passing a first material through two receptacles connected in series, the first receptacle having said first material periodically charged therein and discharged therefrom and the second receptacle being intermittently charged from said first receptacle and continuously discharged, continuously weighing the contents of said second receptacle during the period that said first receptacle is not being discharged to produce a signal corresponding to the rate of change of weight of said second receptacle, continuously weighing the combined contents of said first and second receptacles during the period that said first receptacle is discharging thereby producing a second signal of equivalent value to said first signal and corresponding to said rate of change of Weight, successively automatically comparing said measured signals to a first command signal representative of a predetermined desired rate of flow and applying the resultant of said comparison to adjust the rate of flow of said first material from said second receptacle to conform said measured signals to said first command signal representative of a predetermined desired rate of flow and applying the resultant of said comparison to adjust the rate of flow of said first material from said second receptacle to conform said measured signals to said first command signal; passing a hydratable inorganic detergent builder salt through third and fourth receptacles connected in series, said third receptacle having said builder salt periodically charged therein and discharged therefrom and said fourth receptacle being intermittently charged from said third receptacle and continuously discharged, continuously weighing the contents of said fourth receptacle during the period said third receptacle is not being discharged to produce a third signal corresponding to the rate of change of Weight of said fourth receptacle, continuously weighing the combined contents of said third and fourth receptacles during the period that said third receptacle is discharging thereby producing a fourth signal of equivalent value to said third signal corresponding to said rate of change of weight of said fourth receptacle, successively automatically comparing said third and fourth signals to a second command signal representative of a predetermined desired rate of flow and applying the resultant thereof to adjust the rate of flow of material discharged from said fourth receptacle to correspond to said second command signal; continuously intimately admixing said first material from said second receptacle with material discharged from said fourth receptacle in the presence of an inert normally gaseous material under a pressure in excess of about 20 p.s.i.g. whereby a low density detergent product is formed, and drying said product.

12. Method for the production of low bulk density detergent compositions comprising; passing a premix comprising a continuous aqueous liquid phase and a discontinuous phase containing a water-soluble organic detergent through two receptacles connected in series, the first receptacle having said premix periodically charged therein and discharged therefrom and the second receptacle being intermittently charged from said first receptacle and continuously discharged, continuously weighing the contents of said second receptacle during the period that said first receptacle is not being discharged and producing a signal corresponding to the rate of change of weight of said second receptacle, continuously weighing the combined contents of said first and second receptacles, during the period that said first receptacle is discharging thereby producing a second signal of equivalent value to said first signal and corresponding to said rate of change of weight, successively automatically comparing said measured signals to a first command signal and applying the resultant of said comparison to control the rate of flow of said premix from said second receptacle to adjust the rate of flow of said premix from said second receptacle to conform to said first command signal; passing an additive material comprising a hydratable inorganic detergent builder salt selected from the group consisting of alkali and alkaline earth metal phosphates, sodium carbonate, sodium silicate, magnesium sulfate and sodium tetraborate through third and fourth receptacles connected in series, said third receptacle having said additive material periodically charged therein and discharged therefrom and said fourth receptacle being intermittently charged from said third receptacle and continuously discharged, continuously weighing the contents of said fourth receptacle during the period said third receptacle is not being discharged to produce a third signal corresponding to the rate of change of weight of said fourth receptacle, continuously weighing the combined contents of said third and fourth receptacles during the period that said third receptacle is discharging thereby producing a fourth signal of equivalent value to said third signal corresponding to said rate of change of weight of said fourth receptacle, successively automatically comparing said third and fourth signals to a second command signal and applying the resultant thereof to adjust the rate of flow of said additive material from said fourth receptacle to correspond to said second command signal; combining the stream of premix flowing from said second receptacle with the stream of additive material from said fourth receptacle; comparing the rates of flow of said streams and r adjusting said rates of flow relative to each other upon variations in either to conform to a predetermined ratio therebetween; continuously metering to the combined streams an inert normally gaseous material and a strong base selected from the group consisting of alkali metal carbonates, silicates, oxides, hydroxides, and orthophosphates, and alkaline earth metal oxides and hydroxides; mixing the resulting combination of components under superatmospheric pressure in excess of about 20 p.s.i.g. and at a shean. factor in excess of about five to intimately mix the components thereof and to uniformly disperse said gaseous substance therethrough in discrete gaseous bodies, the majority of which have an average diameter less than about 0.085 millimeter; terminating said mixing; gradually reducing the pressure to atmospheric pressure thereby avoiding sudden changes in pressure whereby a low density foraminous detergent product is formed, and drying said product.

13. A continuous process for the production of low bulk density detergent compositions comprising, forming a slurry having a continuous aqueous phase and at least about 70 percent by weight of a dispersed phase contain- I ing a water-soluble organic detergent and an hydratable inorganic sodium salt selected from the group consisting of alkaline and neutral detergent builder salts, mixing said slurry in the presence of an inert normally gaseous sub- I stance at a high shear rate and under pressure in excess of about 20 p.s.i.g., and gradually reducing the pressure I to atmospheric pressure at the termination of said mixing step thereby avoiding sudden changes in pressure, wheret sodium dodecyl benzene sulfonate, sodium pentadecyl.

benzene sulfonate wherein the dodecyl and pentadecyl groups are derived from a propylene polymer, sodium keryl benzene sulfonate, potassium dodecyl benzene sulfonate, sodium coconut oil monoglyceride monosulfate, sodium lauryl sulfate, sodium coconut fatty alcohol sulfate, potassiuum coconut fatty alcohol sulfate, sodium palm kernel oil alcohol sulfate, sodium coconut fatty acid ethanolamide sulfate, sodium lauric acid amide of taurine, polyethylene oxide condensates with alkyl phenols having 6 to 20 carbons in the alkyl group, polyethylene oxide esters with lauric acid containing between about 16 to 20 ethylene oxide groups, polyethylene oxide condensates with lauryl, myristyle, oleyl and stearyl alcohols containing 6 to 30 moles ethylene oxide, polyoxyethylene oxide condensates with coconut fatty acid amide containing about 10 to 50 moles ethylene oxide, polyoxyethylene condensates with polypropylene glycol which condensates contain 80% ethylene oxide and have a molecular weight of about 1700, iso-octyl phenoxy polyoxyethylene ethanol having about 8.5 ethanoxy groups per molecule, cetyl trimethyl ammonium chloride, cetyl pyridinium chloride, sodium dodecyl beta-elanine, sodium laurate, sodium myristate, potassium palmitate, and triethanolamine stearate and about 20 to 80 percent by Weight of an hydratable inorganic sodium salt selected from the group consisting of alkaline and neutral detergent \builder salts, mixing said slurry in the presence of an inert normally gaseous substance selected from the group consisting of air, nitrogen, oxygen, and carbon dioxide at a shear fac-,

tor in excess of about five and under a pressure in excess of about 20 p.s.i.g., and reducing the pressure to atmospheric pressure at the termination of said mixing step, whereby the product forms a solid, porous detergent product.

15. A continuous process for the production of low bulk density detergent compositions comprising, forming a slurry of a continuous aqueous phase and 1) a water soluble organic detergent selected from the group consisting of anionic, nonionic, cationic, and ampholytic,

gaseous bodies, the majority of which have an average diameter of less than about 0.085 millimeter,;terminating said mixing, and gradually reducing the pressure of said slurry, whereby there is obtained a particulate, cellular:

detergent having a bulk density of less than about 0.45 gram per cubic centimeter,

16. A continuous process for the production of low bulk density detergent compositions comprising; forming a slurry having a continuous aqueous phase and dispersed therein a water-soluble organic detergent and a hydratable inorganic sodium salt selected from the group consisting of alkaline and neutral detergent builder salts the solids content of said slurry being in excess of about 70 percent; mixing said slurry in the presence of an inert normaly gaseous substance for a period of up to about 30 seconds and at a pressure in excess of about 40 ounds per square inch gauge and a shear factor in excess of about 6.5 to intimately mix the components thereof and to uniformly disperse said gaseous substances therethrough in discrete gaseous bodies, the majority of which have an average diameter less than about 0.054 millimeter; terminating said mixing; and passing the resulting intimately mixed product through a decompression zone having a ratio of length to diameter of at least 10: 1, whereby there is obtained a detergent having a substantially uniform cell structure and a bulk density of less than about 0.45 gram per cubic centimeter.

17. A continuous process for the production of low bulk density detergent compositions comprising, forming a slurry having a continuous, aqueous liquid phase and, dispersed in said aqueous liquid phase, up to about 65 percent by weight of a water-soluble organic detergent thereby forming a premix, commingling with said premix a caustic and between about 20 and 80 percent by weight of a material capable of reaction with water in the presence of said caustic to produce a water soluble alkali metal polyphosphate hydrate, immediately thereafter crutching the resulting commingled stream at a shear factor in excess of about five and in the presence of an inert normally gaseous substance under a pressure in excess of about 20 p.s.i.g. thereby initiating a reaction which converts said material to said water soluble alkali metal polyphosphate hydrate and recovering a foramino-us, particulate product containing said alkali metal polyphosphate hydrate and said product having a bulk density of less than about 0.45 gram per cubic centimeter.

18. A continuous process for the production of low density detergent compositions comprising, forming a slurry of water and a water soluble organic detergent selected from the group consisting of anionic, nonionic, cationic, and ampholytic detergents, adding to said slurry a material capable of reaction with water to form a hydrate whereby to impart a relatively high structural strength to the product by the removal of the free water from the slurry and an inert normally gaseous substance, mixing said slurry immediately thereafter in the presence of both of said material and said normally gaseous substance at a high shear rate and under a pressure in excess of about 20 p.s.i.g., said slurry having a solids content of at least about 70 percent at the time of high shear mixing, terminating said mixing step, and reducing said pressure to atmospheric pressure whereby a low-density, particulate, cellular detergent product is formed.

19. A continuous process for the production of low bulk density detergent compositions comprising, forming a slurry of water and about 2 to 65 percent by weight of a water-soluble organic detergent selected from the group consisting of alkyl benzene sulfonates wherein the alkyl group has about 8 to 16- carbon atoms, sulfated and sulfonated compounds having a radical containing 8 to 22 carbon atoms in its molecular structure, polyethylene oxide condensates of between about 5 and 50 ethylene oxide groups with a hydrophobic organic group containing at least about 8 carbon atoms, and alkali metal, amine, and ammonium salts of fatty acids having from 10 to 18 carbon atoms, adding to said slurry an inert normally gaseous substance and 2080 percent by weight of a hydratable material selected from the group consisting of alkali and alkaline earth metal phosphates, sodium carbonate, sodium silicate, magnesium sulfate, and sodium tetraborate, mixing said slurry immediately after said addition in the presence of said normally gaseous substance selected from the group consisting of air, nitrogen, oxygen, and carbon dioxide and said material at a shear factor in excess of five and under pressure in excess of about 20 pounds per square inch gauge to uniformly disperse said gaseous substance therethrough as individual, small, gaseous bodies, the majority of Which have an average diameter of less than about 0.054 millimeter, terminating said mixing step, and reducing said pressure to atmospheric pressure whereby a lowdensity, foraminous detergent product is formed.

20. A continuous process for the production of low bulk density detergent compositions comprising; forming a slurry of a water-soluble organic detergent and water; adding to said slurry an inert normally gaseous substance and a hydratable inorganic detergent builder salt, the solids content of said slurry after said addition being in excess of about 75 percent; mixing said slurry immediately after said addition in the presence of said normally gaseous substance and said material at a shear factor in excess of five and under a pressure in excess of about 20 pounds per square inch gauge to uniformly disperse said gaseous substance therethrough as discrete gaseous bodies the majority of which have an average diameter less than about 0.054 millimeter; terminating said mixing; and passing the resulting intimately mixed product through a decompression zone having a ratio of length to diameter of at least 10:1 whereby a low bulk density foraminous detergent is formed.

21. A continuous process for the production of low bulk density detergent compositions comprising; forming a slurry of water and a water-soluble organic detergent; adding to said slurry an inert normally gaseous substance and a powdered hydratable inorganic detergent builder salt at least percent of the particles of which have a diameter smaller than about microns, and the solids content of said slurry after said addition being in excess of about 75 percent; initiating mixing of said slurry within about five seconds of the addition of the last additive at a shear factor in excess of 6.5 and under a pressure in excess of about 40 pounds per square inch gauge; continuing said mixing for up to about thirty seconds to intimately mix said slurry and uniformly disperse said gaseous substance therethrough as discrete gaseous bodies the majority of which have an average diameter less than about 0.085 millimeter; terminating said mixing; and passing the resulting intimately mixed product through a decompression zone having a ratio of length to diameter of at least 10:1 whereby a low bulk density foraminous detergent is formed.

22. A continuous process for the production of a low bulk density detergent composition comprising admixing a water-soluble organic detergent selected from the group consisting of anionic, nonionic, cationic, and ampholytic detergents and water to form a slurry, adding to said slurry between about .20 and 80 percent by weight of an alkali metal trimetaphosphate and an inert normally gaseous substance, mixing said slurry in the presence of said material and said inert normally gaseous substance at a high shear rate and under pressure in excess of about 20 pounds per square inch gauge to uniformly disperse said gaseous substance therein, terminating said mixing step, and reducing said pressure to atmospheric pressure whereby a low-density, porous detergent product is formed.

23. A continuous process for the production of low bulk density detergent compositions comprising; slurrying a water-soluble organic detergent in water; adding to said slurry an inert normally gaseous substance, an alkali metal trimetaphosphate, and a caustic, the solids content of said slurry after said addition being in excess of about 75 percent; mixing said slurry immediately after said addition in the presence of said normally gaseous substance and said material at a shear factor in excess of five and under a pressure in excess of about 20 pounds per square inch gauge to uniformly disperse said gaseous substance therethrough as discrete gaseous bodies the majority of which have an average diameter less than about 0.054 millimeter; terminating said mixing; and passing the resulting intimately mixed product through a decompression zone wherein the pressure is gradually reduced to atmospheric whereby a low bulk density foraminous detergent is formed.

24. A continuous process for the production of low bulk density detergent compositions comprising; forming an aqueous slurry containing about two to 65 parts by weight of a water-soluble organic detergent; adding to said slurry an inert normally gaseous substance, about 3050 parts by weight of sodium trimetaphosphate in particulate form, at least about 90 percent of the particles of sodium trimetaphosphate having a diameter of less than about 150 microns, and an alkali hydroxide in amounts equal to between about 1.4 and mole equivalents per mole equivalent of said sodium trimetaphosphate, the solids content of said slurry after said addition being in excess of about 75 percent; initiating mixing of said slurry within about five seconds of the addition of the last additive at a shear factor in excess of 6.5 and under a pressure in excess of about 20 pounds per square inch gauge; continuing said mixing for up to about 30 seconds to intimately mix said slurry and to uniformly disperse said gaseous substance therethrough as discrete gaseous bodies the majority of which have an average diameter less than about 0.085 millimeter; terminating said mixing; and passing the resulting intimately mixed product through a decompression zone having a ratio of length to diameter of at least 10:1 whereby a low bulk density foraminous detergent is formed.

25. Method for the production of low bulk density detergent compositions comprising; passing a feed stream comprising a continuous aqueous liquid phase and a discontinuous phase containing an organic detergent and an inorganic sodium salt selected from the group consisting of alkaline and neutral detergent builder salts through two receptacles connected in series, the first having said feed stream periodically charged therein and discharged therefrom and the second receptacle being intermittently charged from said first receptacle and continuously discharged, continuously weighing the contents of said second receptacle during the period that said first receptacle is not being discharged to produce a signal corresponding to the rate of change of weight of said second receptacle, continuously weighing the combined contents of said first and second receptacles, during the period that said first receptacle is discharging thereby producing a second signal of equivalent value to said first signal and of a value corresponding to said rate of change of weight, successively comparing said measured signals to a predetermined first command signal and applying the resultant of said comparison to control the rate of flow of said feed stream from said second receptacle to adjust the rate of flow of said feed stream from said second receptacle to conform to said predetermined first command signal; passing an additive stream comprising a hydratable material through third and fourth receptacles connected in series, said third receptacle having said additive stream periodically charged therein and discharged therefrom and said fourth receptacle being intermittently charged from said third receptacle and continuously discharged, continuously weighing the contents of said fourth receptacle during the period said third receptacle is not being discharged to produce a third signal corresponding to the rate of change of weight of said fourth receptacle, contiuously weighing the combined contents of said third and fourth receptacles during the period that said third receptacle is discharging thereby producing a fourth signal of equivalent value to said third signal corresponding to said rate of change of weight of said fourth receptacle, successively comparing said third and fourth signals to a predetermined second command signal and applying the resultant thereof to adjust the rate of flow of said additive stream from said fourth receptacle to correspond to said predetermined second command signal; adding the additive stream from said fourth receptacle to the feed stream flowing from said second receptacle; comparing the rates of flow of said streams and adjusting said rates of flow relative to each other upon variations in either to conform to a predetermined ratio therebetween; continuously metering to the feed stream an inert normally gaseous material; mixing the resulting combination of components under superatmospheric pressure and at a high shear rate to intimately mix the components thereof and to uniformly disperse said gaseous substance therethrough as discrete gaseous bodies; terminating said miX- ing; reducing the pressure to atmospheric pressure whereby a low density foam-like detergent product is formed; and drying said product.

26. Method for the production of low bulk density detergent compositions comprising; passing a premix comprising a continuous aqueous liquid phase and a discontinuous phase containing from about 2 to about 65 percent by weight of an organic detergent and up to about 6 percent by weight of a water soluble hydrotropic alkyl sulfonate salt through two receptacles connected in series, the first having said premix periodically charged therein and discharged therefrom and the second receptacle being intermittently charged from said first receptacle and continuously discharged, continuously weighing the contents of said second receptacle during the period that said first receptacle is not being discharged to produce a signal corresponding to the rate of change of Weight of said second receptacle, continuously weighing the combined contents of said first and second receptacles, during the period that said first receptacle is discharging thereby producing a second signal of equivalent value to said first signal of a value corresponding to said rate of change of Weight, successively comparing said measured signals to a predetermined first command signal and applying the resultant of said comparison to control the rtae of flow of said premix from said second receptacle to adjust the rate of flow of said premix from said second receptacle to conform to said predetermined first command signal; passing an additive material comprising from about 20 to percent by Weight of hydratable alkali metal trimetaphcsphate through third and fourth receptacles connected in series, said third receptacle having said additive material periodically charged therein and discharged therefrom and said fourth receptacle being intermittently charged from said third receptacle and continuously discharged, continuously Weighing the contents of said fourth receptacle during the period said third receptacle is not being discharged toproduce a third signal corresponding to the rate of change of weight of said fourth receptacle, continuously weighing the combined contents of said third and fourth receptacles during the period that said third receptacle is discharging thereby producing a fourth signal of equivalent value to said third signal corresponding to said rate of change of weight of said fourth receptacle, successively comparing said third and fourth signals to a predetermined second command signal and applying the re-'- sultant thereof to adjust the rate of flow of said additive material from said fourth receptacle to correspond to said predetermined second command signal; combining the stream of premix flowing from said second receptacle with the stream of additive material from said fourth receptacle; comparing the rates of flow of said streams and adjusting said rates of flow relative to each other upon variations in either to conform to a predetermined ratio therebetween; continuously metering to the combined streams an inert normally gaseous material; continuously adding an alkali metal hydroxide in amounts of between about 1.4 and 10 mole equivalents per mole equivalent of said hydratable alkali trimetaphosphate to form a combined mixture having a solids content above about 70 percent; mixing the resulting combination of components under a pressure in excess of 3,515, 672 25 26 about 20 pounds per square inch gauge and at a high References Cited shear rate for not more than about thirty seconds to inti- UNITED STATES PATENTS mately mix the components thereof and to uniformly dis- 2,715,610 8/1955 Thompson perse said gaseous substance therethrough as discrete gaseous bodies the majority of which have an average diam- 5 LEON D. ROSDOL, Primary Examiner eter less than about 0.085 millimeter; terminating said WILLIS, Assistant Examiner mixing; reducing the pressure to atmospheric pressure whereby a low density foam-like detergent product is US. Cl. X.R. formed, and drying said product. 252--137, 138; 23-230, 252, 253

UNITED STATES PA'IENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,515,672 Dated June 2, IQ'YO Inventor(s) Lowell A. Ledgett and Martin D. Reinish It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 3, "ovide" should read --oxide--; line 30, "ingredent should read --ingredient--; and line 40, "alamine" should read --alanine--. Column 6, line 63, after "mixing" add --step--. Column 8, line 6 4, after "receptacles" add "-22, full and the first and second intermittent receptacles--. Column 1 line 9, "tubes" should read --tubs--; in Table I, the heading "factor" should read -Shear Factor--; and heading "sTs 1" should read --STS 1o--. Column 16, line 6, "50" should read "50 Column 20, line do, "beta-elanine" should read beta-alanine--. Column 21, line 5, normaly" should read --normally--. Column 23, line 1 after "alkalf add --metal--. Column 2 line 20, after "alkyl add --aryl--; and line 72, after "alkali" add --metal--.

olGNED AND QEALEU Attest:

FlewherJrmm 1:. JR- Gomnissioner of Patents FORM P0-1D50 (10-69) uscomupoc 60:76AM 0 u s, savanna" nun-Inc orrlcz nu o-au-su 

